One thing when painting aluminum ,, your going to want to use an etching primer of some type if you ever want it to stick right,,, or at all. What ever the paint is you use. You can use the multiple steps with the acid itself, or just use a Sickens or the Dupont "Veri Prime" ,both are 2 part acid etching primers,, they both work awesome,,WEAR GLOVES AND A RESPIRATOR,, for sure !!!!
No Joke!! That shit is brutal on your hide and lungs,,,,duh,,,, IT ETCHES METAL !!!!
It's 50% acid, either hydrochloric or phosphoric acid if I remember right???? Don't recall which. At any rate be careful with it, even when you scotchbrite it for final painting, the dust will still bother you, even after it's dried. Nasty stuff, but it really works.
Had lots of experience using that stuff doing resto's and repairs on Ferrari's and Lambo's,, and it really works well and holds like crazy, that shit won't flake off on ya.